1. Field of the Invention
The present invention relates to a scrolling apparatus for repositioning an image relative to a display screen. More particularly, the invention relates to a scrolling apparatus that utilizes a stopping and locking system to terminate its rotation in a particular direction when the user reaches the end of a document. The invention has application to input devices, such as a mouse, trackball, or keyboard, to scroll an image relative to a display screen.
2. Description of Background Art
The viewable contents of a computer file, such as a text document, spreadsheet, digital photograph, Web page, or other image rendered on a conventional display screen, may possess a size exceeding the viewable boundaries of the display screen. To address this issue, an individual may utilize a scrolling apparatus to reposition the image relative to the display screen, thereby permitting the individual to view portions of the computer file not currently rendered. As utilized herein, scrolling describes a translatory movement of the image relative to the display screen and in a particular direction. For example, scrolling down generally describes a movement of the image relative to the display screen so as to produce an effect of moving downward in the image. Similarly, scrolling up, scrolling left, and scrolling right generally describe movement of the image relative to the display screen so as to produce an effect of moving the image upward, left, and right, respectively.
Scrolling apparatuses have been incorporated into a plurality of peripheral input devices, including computer mice and trackball pointing devices, and keyboards, for example. An example of a computer mouse incorporating a scrolling apparatus is disclosed in U.S. Pat. No. 5,912,661 to Siddiqui, which is hereby incorporated by reference. Elements of the scrolling apparatus include a finger-engageable scroll wheel and a sensor assembly. The scroll wheel is mounted within a housing of the computer mouse, and a portion of the scroll wheel protrudes from an opening in the housing to permit an individual to selectively rotate the scroll wheel. The sensor assembly detects rotation of the scroll wheel and transmits a corresponding signal to a host computer, thereby directing the image to scroll relative to the display screen. By rotating the scroll wheel in a first direction, an image on a display screen may be scrolled upward, for example. Similarly, by rotating the scroll wheel in an opposite second direction, the image may be scrolled downward. Accordingly, a scroll wheel may be operated in a bi-directional manner to vertically scroll the image relative to the display screen.
Based on the size of the document the user is scrolling within, the user may have to rotate the scroll wheel a large number of revolutions to reach a desired location in the document. Rather than scrolling slowly through the document, users commonly rotate the scroll wheel many times in a rapid manner because a slow controlled rotation can be time consuming. However, under such circumstances, it is common that the user will unintentionally “over-scroll” past the point of the intended location, and scroll to the end of the document, with additional scrolling commands being sent because there is an attempt to over-scroll past the end of the document. This results in the computer system scrolling the image to the end of the document, and then attempting to process extra scrolling commands that are not performed. In addition to wasted finger motion by the user, this results in a loss of efficiency in operating the computer.